scholarly journals Volcanic precursors in light of eruption mechanisms at Vesuvius

2013 ◽  
Vol 56 (4) ◽  
Author(s):  
Roberto Scandone ◽  
Lisetta Giacomelli
Keyword(s):  
Structural Condition ◽  
Magma Ascent ◽  
Caldera Collapse ◽  
Parallel Increase ◽  
Strombolian Eruptions ◽  
Explosive Phase ◽  
The One ◽  
Effusive Eruptions ◽  
Quiescent Stage ◽  
Violent Strombolian Eruptions

<p>Vesuvius entered a quiescent stage after the eruption of March-April 1944. The eruption was not much different or larger than other before, like for example the one of 1906, but it occurred at the end of a long period during which it was observed a decreasing trend of explosivity of eruptions [Scandone et al. 2008]. The parallel increase in the frequency of slow effusive eruptions, with respect to violent strombolian eruptions, point out to a process of average slower rate of magma ascent possibly due to a progressive sealing of the ascent path of magma to the surface. The small caldera collapse following the 1944 explosive phase effectively sealed the upper conduit, and since then the volcano entered a quiescence stage that was unusual with respect to the pattern of activity of the previous 300 years when the maximum repose time had been of 7 years (after the eruption of 1906). Most of the uncertainty on the duration of the present stage and character of a future renewal of activity derives by the basic questions regarding the nature of the current repose: due to a diminished supply of magma, related with structural condition or a sealing of the upper ascent path to the surface? Possibly the variation of structural conditions caused average slower ascent rates of magma favoring its cooling in the upper part of the crust, and effectively sealing the ascent path.</p>

Dynamics of large effusive eruptions driven by caldera collapse

Nature ◽  
2021 ◽  
Vol 592 (7854) ◽  
pp. 392-396
Author(s):  
Alberto Roman ◽  
Paul Lundgren
Keyword(s):  
Caldera Collapse ◽  
Effusive Eruptions

scholarly journals Symptom shift in 200 patients with H63D syndrome associated with abnormal TCS findings in substantia nigra

2021 ◽  
Author(s):  
Dr. Carolina Diamandis ◽  
David Seideman ◽  
Jacob S Adams ◽  
Riku Honda ◽  
Marianne Kaufmann ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Substantia Nigra ◽  
Patient Population ◽  
Inverse Correlation ◽  
Transcranial Sonography ◽  
The Other ◽  
Significant Finding ◽  
Other Hand ◽  
Parallel Increase ◽  
The One

In a study on the prevention of injury in patients with H63D syndrome and cataplexy, statistical analysis revealed an unexpected but clinically highly significant finding. Apparently, in this patient population, an inverse correlation exists between the severity of tic symptomatology on the one hand and narcolepsy with cataplexy on the other hand, as well as a parallel increase in the typical signs of degeneration observed in transcranial sonography of the substantia nigra. This finding has clinically far-reaching implications.

A user-friendly probabilistic earthquake source inversion framework for joint inversion of seismic, geodetic, and gravitational signals - The Grond toolkit

2020 ◽  
Author(s):  
Sebastian Heimann ◽  
Marius Isken ◽  
Daniela Kühn ◽  
Hannes Vasyura-Bathke ◽  
Henriette Sudhaus ◽  
...  
Keyword(s):  
Open Source ◽  
Joint Inversion ◽  
Moment Tensor ◽  
Source Parameters ◽  
Seismic Source ◽  
Magma Ascent ◽  
Caldera Collapse ◽  
Waveform Data ◽  
Trade Offs ◽  
Finite Fault

&lt;p&gt;Seismic source and moment tensor waveform inversion is often ill-posed or non-unique if station coverage is poor or signals are weak. Three key ingredients can help in these situations: (1) probabilistic inference and global search of the full model space, (2) joint optimisation with datasets yielding complementary information, and (3) robust source parameterisation or additional source constraints. These demands lead to vast technical challenges, on the performance of forward modelling, on the optimisation algorithms, as well as on visualisation, optimisation configuration, and management of the datasets. Implementing a high amount of automation is inevitable.&lt;/p&gt;&lt;p&gt;To tackle all these challenges, we are developing a sophisticated new seismic source optimisation framework, Grond. With its innovative Bayesian bootstrap optimiser, it is able to efficiently explore large model spaces, the trade-offs and the uncertainties of source parameters. The program is highly flexible with respect to the adaption to specific source problems, the design of objective functions, and the diversity of empirical datasets.&lt;/p&gt;&lt;p&gt;It uses an integrated, robust waveform data processing, and allows for interactive visual inspection of many aspects of the optimisation problem, including visualisation of the result uncertainties. Grond has been applied to CMT moment tensor and finite-fault optimisations at all scales, to nuclear explosions, to a meteorite atmospheric explosion, and to volcano-tectonic processes during caldera collapse and magma ascent. Hundreds of seismic events can be handled in parallel given a single optimisation setup.&lt;/p&gt;&lt;p&gt;Grond can be used to optimise simultaneously seismic waveforms, amplitude spectra, waveform features, phase picks, static displacements from InSAR and GNSS, and gravitational signals.&lt;/p&gt;&lt;p&gt;Grond is developed as an open-source package and community effort. It builds on and integrates with other established open-source packages, like Kite (for InSAR) and Pyrocko (for seismology).&lt;/p&gt;

scholarly journals Support tools to predict the critical structural condition of uninspected pipes for case studies of Germany and Colombia

2018 ◽  
Vol 13 (4) ◽  
pp. 794-802 ◽  
Author(s):  
Nathalie Hernández ◽  
Nicolas Caradot ◽  
Hauke Sonnenberg ◽  
Pascale Rouault ◽  
Andrés Torres
Keyword(s):  
Case Studies ◽  
Asset Management ◽  
Structural Condition ◽  
Strategic Investment ◽  
Sewer Pipes ◽  
Support Tool ◽  
Deviation Analysis ◽  
Management Objectives ◽  
The One ◽  
Different Characteristics

Abstract Several deterioration models have been used to predict the structural condition of sewer pipes, and some have been applied in different cities in the world. However, each one of these models has not been proved simultaneously for case studies with different characteristics (topographic conditions, soil uses, demographic growth, utilities' service operation and city's dynamic) and the use of their predictions have not been analyzed to support different management objectives. Therefore, the objective of this work was to assess the prediction results of two models (based on Logistic Regression and Random Forest (RF) methods), which previously have been identified as successful in other experiences, for two different case studies (a city in Colombia and a city in Germany). The prediction assessment was carried out by three analysis techniques (Positive Likelihood Rate (PLR) index, performance curve and deviation analysis). According to the results, we found that: (i) the model based on RF was the one that could be useful as a support tool in the sewer asset management of both case studies; (ii) for the German city, the prediction results could be useful for designing strategic investment plans in order to know the number of pipes that the utility should rehabilitate each year; and (iii) for the Colombian city, the predictions are appropriate to make decisions concerning inspection or rehabilitation plans, since the probability of identifying the sewer's assets in critical condition (C4) correctly (according to the analysis of the sample of the 10% of sewers with the highest probability to be in this condition) is around 63% and could be 83% if the stakeholders also consider in these plans the misclassification of those pipes in a bad structural condition (C3).

The correlation between the increase in slow outward current and in contraction induced by caffeine, ryanodine, and rapid cooling in voltage-clamped frog muscle fibers

1991 ◽  
Vol 69 (6) ◽  
pp. 859-864 ◽  
Author(s):  
Mohammad Nasri-Sebdani ◽  
Flavien Traoré ◽  
Aklesso Mouzou ◽  
Christian Cognard ◽  
Daniel Potreau ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Release ◽  
Muscle Fibers ◽  
Outward Current ◽  
Frog Muscle ◽  
Rapid Cooling ◽  
Key Words Skeletal Muscle ◽  
Parallel Increase ◽  
The One ◽  
Sarcoplasmic Reticulum Calcium

The effects of caffeine, ryanodine, and rapid cooling were tested on the depolarization-induced contraction and the apamin-insensitive slow outward current (Iso) of voltage-clamped (double mannitol gap) single frog muscle fibers. Subthreshold caffeine concentrations (0.5–2 mM) induced a monotonic increase in contractile and Iso amplitude. Whatever the concentration, the increase in contraction was roughly twice the one in current. Similar results were obtained upon rapid cooling (20–4 °C) in the presence of 0.5 mM caffeine. In the absence of external Na+ (choline-substituted) 10−5 M ryanodine induced a delayed increase (≈30 min) in contraction and in current, shortly before the development of a drastic and irreversible contracture. Here again, the increase in contraction was twice that in current. In the presence of 5 mM tetraethylammonium (TEA) and (or) 25 nM charybdotoxin, 2 mM caffeine still induced a strong facilitating effect on contraction but the parallel increase in current was strongly reduced. The linear relationship between the increase in current and contractile amplitude has a slope ≈0.5 (whatever the drug used to increase contractility); it is ≈0.1 in the presence of TEA and (or) charybdotoxin. In conclusion, provided the changes in contractile amplitude are caused by parallel changes in depolarization-induced sarcoplasmic reticulum Ca2+ release, about 50% of the apamin-insensitive Iso is controlled by internal Ca2+ release. The main part of this current corresponds to the TEA- and charybdotoxin-sensitive component of Iso.Key words: skeletal muscle, voltage clamp, Ca2+-dependent K+ current, sarcoplasmic reticulum calcium release, caffeine, ryanodine, charybdotoxin.

Explosive volcanism on Santorini, Greece

1989 ◽  
Vol 126 (2) ◽  
pp. 95-126 ◽  
Author(s):  
T. H. Druitt ◽  
R. A. Mellors ◽  
D. M. Pyle ◽  
R. S. J. Sparks
Keyword(s):  
Explosive Volcanism ◽  
Volcanic Field ◽  
Pyroclastic Flows ◽  
Coarse Grained ◽  
Magma Ascent ◽  
Explosive Eruptions ◽  
Caldera Collapse ◽  
Caldera Wall ◽  
Magma Chambers ◽  
Facies Associations

AbstrctSantorini volcanic field has had 12 major (1–10 km3 or more of magma), and numerous minor, explosive eruptions over the last ~ 200 ka. Deposits from these eruptions (Thera Pyroclastic Formation) are well exposed in caldera-wall successions up to 200 m thick. Each of the major eruptions began with a pumice-fall phase, and most culminated with emplacement of pyroclastic flows. Pyroclastic flows of at least six eruptions deposited proximal lag deposits exposed widely in the caldera wall. The lag deposits include coarse-grained lithic breccias (andesitic to rhyodacitic eruptions) and spatter agglomerates (andesitic eruptions only). Facies associations between lithic breccia, spatter agglomerate, and ignimbrite from the same eruption can be very complex. For some eruptions, lag deposits provide the only evidence for pyroclastic flows, because most of the ignimbrite is buried on the lower flanks of Santorini or under the sea. At least eight eruptions tapped compositionally heterogeneous magma chambers, producing deposits with a range of zoning patterns and compositional gaps. Three eruptions display a silicic–silicic + mafic–silicic zoning not previously reported. Four eruptions vented large volumes of dacitic or rhyodacitic pumice, and may account for 90% or more of all silicic magma discharged from Santorini. The Thera Pyroclastic Formation and coeval lavas record two major mafic-to-silicic cycles of Santorini volcanism. Each cycle commenced with explosive eruptions of andesite or dacite, accompanied by construction of composite shields and stratocones, and culminated in a pair of major dacitic or rhyodacitic eruptions. Sequences of scoria and ash deposits occur between most of the twelve major members and record repeated stratocone or shield construction following a large explosive eruption.Volcanism at Santorini has focussed on a deep NE–SW basement fracture, which has acted as a pathway for magma ascent. At least four major explosive eruptions began at a vent complex on this fracture. Composite volcanoes constructed north of the fracture were dissected by at least three caldera-collapse events associated with the pyroclastic eruptions. Southern Santorini consists of pryoclastic ejecta draped over a pre-volcanic island and a ridge of early- to mid-Pleistocene volcanics. The southern half of the present-day caldera basin is a long-lived, essentially non-volcanic, depression, defined by topographic highs to the south and east, but deepened by subsidence associated with the main northern caldera complex, and is probably not a separate caldera.

Explosive dynamics of violent Strombolian eruptions: The eruption of Parícutin Volcano 1943–1952 (Mexico)

2008 ◽  
Vol 271 (1-4) ◽  
pp. 359-368 ◽  
Author(s):  
L. Pioli ◽  
E. Erlund ◽  
E. Johnson ◽  
K. Cashman ◽  
P. Wallace ◽  
...  
Keyword(s):  
Violent Strombolian ◽  
Strombolian Eruptions ◽  
Violent Strombolian Eruptions

scholarly journals An Overview of the Mafic and Felsic Monogenetic Neogene to Quaternary Volcanism in the Central Andes, northern Chile (18-28°Lat.S)

2020 ◽  
Author(s):  
Gabriel Ureta ◽  
Károly Németh ◽  
Felipe Aguilera ◽  
Matias Vilches ◽  
Mauricio Aguilera ◽  
...  
Keyword(s):  
Magma Ascent ◽  
Chemical Compositions ◽  
Northern Chile ◽  
Volcanic Zone ◽  
Quaternary Volcanism ◽  
Groundwater Availability ◽  
The Andes ◽  
Magma Reservoirs ◽  
Strombolian Eruptions ◽  
Magmatic Processes

Monogenetic volcanism produces small eruptive volumes with short eruption history, different chemical compositions, and relatively simple conduit. The Central Volcanic Zone of the Andes is internationally known as a natural laboratory to study volcanism, where mafic and felsic products are present. In this contribution, the spectrum of architectures, range of eruptive styles, lithological features, and different magmatic processes of the mafic and felsic monogenetic Neogene to Quaternary volcanoes from the Central Volcanic Zone of the Andes in northern Chile (18°S-28°S) are described. The major volcanic activity occurred during the Pleistocene, where the most abundant activity corresponds to effusive and Strombolian eruptions. This volcanism is characterized by external (e.g., magma reservoirs or groundwater availability) and internal (e.g., magma ascent rate or interaction en-route to the surface) conditions, which determine the changes in eruptive style, lithofacies, and magmatic processes involved in the formation of monogenetic volcanoes.

scholarly journals Symptom shift in 200 patients with H63D syndrome associated with abnormal TCS findings in substantia nigra

2021 ◽  
Author(s):  
Jacob S. Adams ◽  
Marianne Kaufmann ◽  
Riku Honda ◽  
Lucas Smith ◽  
David Seideman
Keyword(s):  
Statistical Analysis ◽  
Substantia Nigra ◽  
Patient Population ◽  
Inverse Correlation ◽  
Transcranial Sonography ◽  
The Other ◽  
Significant Finding ◽  
Other Hand ◽  
Parallel Increase ◽  
The One

Abstract In a study on the prevention of injury in patients with H63D syndrome and cataplexy, statistical analysis revealed an unexpected but clinically highly significant finding. Apparently, in this patient population, an inverse correlation exists between the severity of tic symptomatology on the one hand and narcolepsy with cataplexy on the other hand, as well as a parallel increase in the typical signs of degeneration observed in transcranial sonography of the substantia nigra. This finding has clinically far-reaching implications.

Decision Tree for Postflooding Roadway Operations

2017 ◽  
Vol 2604 (1) ◽  
pp. 120-130 ◽  
Author(s):  
Yaning Qiao ◽  
Ricardo A. Medina ◽  
Leslie Myers McCarthy ◽  
Rajib B. Mallick ◽  
Jo Sias Daniel
Keyword(s):  
Decision Tree ◽  
Structural State ◽  
Structural Damage ◽  
High Water ◽  
Structural Condition ◽  
High Water Content ◽  
Bayesian Decision ◽  
The Road ◽  
Repair Costs ◽  
The One

When a pavement is flooded, transportation agencies are faced with the decision to leave the road open or close it to traffic. On the one hand, agencies may want to keep the road open and prioritize connectivity if the road serves a critical economic purpose for a region. On the other hand, agencies may choose to close the road to prevent additional structural damage (which may incur significant repair costs) because of high water content in (or even saturation of) the subgrade. Nondestructive testing (NDT) tools such as the falling weight deflectometer (FWD) can be applied to assist decision makers by facilitating a more reliable evaluation of the structural condition of the pavement. Reliable decision making ought to incorporate inherent uncertainties in the process, including the structural state of the pavement after flooding, as well as the reliability of FWD testing and variability in costs. This paper presents a method that uses a Bayesian decision tree approach for highway emergency operations after flooding. Uncertainties in the structural state of the pavement after flooding, NDT, and costs are addressed with Monte Carlo simulations. A case study of a flooded roadway section in North Dakota demonstrated this approach: user delay costs caused by closure of the roadway were explicitly considered. The results of the decision tree analysis provide objective recommendations about opening or closing a road after flooding, as well as whether FWD testing of the flooded road should be conducted once the water recedes.

Sign in / Sign up

Export Citation Format

Share Document